With respect to liquid crystal display devices, research has been conducted into making pixels smaller to increase resolution. For example, in two dimensions, a plurality of pixels are arranged in a lattice pattern. Furthermore, as a thin-film transistor, a double-gate thin-film transistor using a branch portion of a scanning line is known.
It should be noted that the smaller the size of a pixel, the greater the ratio of the area of a gate line, of a signal line, and of a contact hole for a pixel electrode to that of the pixel.